| Although the continuous development of the society makes our life more and more convenit,it also inevitably brings serious environmental pollution.Among all pollution,air pollution will not only affect the climate,industry,agriculture,etc.,but also has adverse effects on human health,so it is very necessary to develop sensors that can quickly detect gas concentration.Until now,metal oxides,carbon nanotubes,conductive polymers and other materials have been widely used in the field of gas sensors.However,the gas sensors based on these materials still have some obvious disadvantages,for example,the high operating temperature and nonprominent selectivity.Nowdays,two-dimensional transition metal dichalcogenides(TMDs)have attracted much attention because of their large specific surface area,microstructure and adjustable electronic structure,which are very beneficial to the design of practical gas sensing devices.According to this,the ReS2-based nanomaterials were synthesized with the metal oxide materials and mesoporous carbon materials by means of reaction route design,ratio control of active components and chemical element doping,also the gas sensitivity of the compound was tested.The main research contents of this paper are summarized as following:1.A simple and rapid hydrothermal synthesis method of ReS2 matrix composite was developed.The ReS2/TiO2 composite was successfully prepared under relatively mild hydrothermal conditions,and its application in gas sensor performance was explored.The required compound was obtained by the reaction of the raw materials in the kettle under high pressure and high heat.The morphology characterization results of the nano-hybrid showed that the ultra-thin nanosheets ReS2 successfully adhered to the TiO2 nanometer band and it was accompanied by Re defects,so the nano-hybrid showed the performance of p-type sensor.The test results of XPS and UPS indicated that electron transfer of different components occurred in the nano-hybrid structure,and electrons were transferred from TiO2 to ReS2.The gas-sensitive test showed that the nano-hybrid had a high response to ammonia gas,and the reaction was carried out at the room temperature,and the detection limit of ammonia gas was 5 ppm.By comparing the performance of the nano-hybrid samples with different mole ratio,we found that when the molar ratio was 2:1 of ReS2 and TiO2,the nano-hybrid material had the best response ability of NH3,it is 5?10 times more than ethanol,formaldehyde and trimethylamine.It indicated that the ratio of ReS2/TiO2 can be regulated in the preparation process to effectively improve the sensing performance of the composite.In addition,the gas sensor based on the nano-hybrid also showed a good response time of 25s to 100ppm ammonia at 15?,and when putting the gas sensor in the air and 100ppm ammonia gas atmosphere for 5 weeks,the material resistance is basically unchanged,indicating that the sensor has a high stability.2.A hydrothermal synthesis way was used to prepare ReS2/CMK-3 and ReS2/N-CMK-3,the composites were successfully prepared under relatively mild hydrothermal conditions and their gas-sensitive properties were investigated.After characterized by SEM and TEM,the composites' morphology was shown that the ultra-thin nanosheets ReS2 were attached to CMK-3 and N-CMK-3 with the micron rod-like network structure.The doping of N forms C-N bond,which changes the arrangement of atoms in the CMK-3 lattice,increasing the concentration of defects in CMK-3,and the concentration of carriers changes accordingly,thus promoting the formation of depletion layer and the change of material resistance in the gas adsorption process,and finally affecting the gas sensing performance.The results of the sensing property of the composites showed when comparing with other gases such as ethanol,acetone,methanol,the sensor has the best response to ammonia gas,and the best operating temperature is room temperature,besides,ReS2/N-CMK-3 composite showing the best property among all materials. |
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